Method of removing sulfur from petroleum hydrocarbons



Patented May 26, 1953 UNITED STATES PATENT QFFECE METHOD 0F REMOVING SULFUIELFROMA PETROLEUM HYDRO'CARBONS Charles. O. Hoover, Houston, Terr.,y assigner to Air Reduction Company, incorporated, New Y'ork-, N. Y., a corporation of New- York Application November 8, 1951, Serial No. l'255,341

(C1. 1mi-28) 19 Claims. l

rllhis` invention relates to the treatment of petroleum hydrocarbons and distillates therefrom and particularly to the removal of undesirable sulphur compounds from petroleum hydrocarbons. Crude petroleum usually contains sulphur in various forms, including hydrogen sulphid'e, mercaptans, disulphides and the like. These and various decomposition products thereof are carried? over in distillateswhich aiord a serious corrosion problem in the treatment and use of the distillates. The sulphur problem, which isespecially troublesome crudes and distillates. from certainl iiel'ds, has never been overcome satisfactorily.

It is the. object of the present invention to provide a simple, effective and relatively inexpensive procedure whereby most of all of the sulphur compounds present in petroleum distillates, such.` as: gasoline, naphtha, kerosene, gas, oil, etc., can be removed eiiectively.

Other objects and advantages of the inventionwill be apparent as it is better understood by reference to the followingY specification and the accompanying drawing, which represents diagrammatically an apparatus suitable for the practice of the invention.

I have. discovered that the sulphur compounds usually present in petroleum distillates` can be removed readily by pas-sing the vapor of the distillate at a temperature between 550 and 950 F; over a catalyst in the presencev oi oxygen. The boiling range and' the types of sulfur compounds contained in the hydrocarbonsl being desulfurized Will dictate the operating tempera.- ture. Hydrocarbons having high boiling points and containing high percentages of residual suliur compounds will require higher temperatures to bring about desulfurization. The most eiiective temperatures are from '75O"850o F.

Catalysts. which may be used include cuprous sulphide, 'and' mixtures of cuprous sulphide with aluminum silicates, or alumina, or mixtures of l alumina and silica.

The cupr'ous' sulphide may be the chemically pure product, or it may contain small amounts of impurities, for example, it may contain as much as 5% ot copper sulphate, or' it may be the impure product produced during the refining of sulphide ores, and sometimes referred to in the copper reiining: industry as copper White metal, and still be effective as a catalyst. The copper White metal usually contains, as impurities, iron, gold', silver and silica in small and varied quantities. The only' advantage in the usel of thisI impure form of cuprous'e sulphide isH n- Ud 2. that it i'sf more readily obtained and' isv cheaper.

Exam-ples 'of aluminum silicates. which may be used with the cu-prous sulphide are natural clays, such. as kaolin, fullers earth, and bentonite, including:` sube-bentonite.

'The mixtures 'of'alumina and silica which may be used? withI the cuprousf sulphide include suela natural materials as. montmorill'onite, or syn'- thetically prepared mixtures containing silica and alumina in varying amounts'. example oi the latter. type of catalyst is the 'product sold underv thel name 'of Sovabead for use inV thermal catalytic cracking.

The catalyst may' bey used in the form of a powder or in the form of beads or pellets, pretera-bly oi smallisizel. Forexaznple, beads having a size of' the order' of 2Go' mesh: ('U.v Si Standard Series) have been ioun'd very' satisfactory since they provide a large surface area and, therefore, have 'greater 'catalytic activi-ty'. However, beads. or: pellets: up to one-eighth or one-half inch in size may be used. The shape of tire beads or' pellets is. not; rrraterial'.4 The only restriction on thev smallness' of the individual particles ist that they must not be so small that vapors` of the petroleum distillate, under." the' existing. pressure, cannot readily passA through the mass of them. It'. is important, from. the: standpoint of size of the apparatus; thatthe catalytic' material afford the maximum surface contact With the vapors which: should.' 'pass freely throughA the catalytic massl together with the oxygen which is supplied thereto.

v'vhilev the usey of cuprous sulphide alone has been found' to bring about the removal of'sul'phur compounds present in petroleum distilates, I prefer tov use a mixture of' cuprous sulphide and alumina, or a silicate, or a silica-alumina material'. Such mixtures may vary from 1% of cuprous: 'sulphide to 99%' of the alumina, or silicate, orsilica-alurnina material to 1% ofthe alumina, orl the' silicate, 'or 'silica-alumina material to 99% or the cuprous. sulphide, although normally a small amount, say from about 2% to* 5%, more or less, -oi a lubricant, such as oil" or graphite, will' bey added to"e the mixture tov assist in the ejection' offthe'beads or pellets, during their formation, from the forming die ofthe pelletizing or beading machine. One catalyst which Was foundi to: be.` particularly eiective in removing larger amounts of sulphur' for a much greater length or time thanY when the components Wereused separately under identical conditions onV the-l same sulphur-containing petroleum distil- 'v lates;` consisted 'or a homogeneous', pell'etizedl mixture of 48% cuprous sulphide, 48% of a silicaalumina material and 4% of graphite.

When the catalyst consists of cuprous sulphide and one or more of the above-named materials, it is preferred that they be formed into a homogeneous mixture and used in the form` of beads or pellets. The catalytic materials may be used in alternate layers, but this ordinarily is not as eiective as when the materials are formed into a homogeneous mixture.

The oxygen used is preferably commercial oxygen of a purity of 99.5% or better, but oxygenenriched air containing more than the normal percentage of oxygen may be used, as for example 25% oxygen or more up to 99.5% oxygen. Even air may be used as the oxidizing agent, but the large percentage of nitrogen introduced with the oxygen will result in some difficulty in the nal condensation of the vapor, necessitating the use of lower condensing temperatures than are otherwise necessary in order to prevent the escape of valuable vapor with the waste nitrogen. The amount of oxygen supplied will depend upon the sulphur content of the vapor which can be determined in advance so that the proper amount of oxygen to oxidize the sulphur present may be introduced. The optimum amount of oxygen can be determined by the ability of the catalyst to maintain a constant rate of sulphur removal.

While not desiring to be limited to any particular theory, it is believed that sulphur contained in the petroleum distille-tes is deposited on the catalyst in such a form that the added oxygen can, under existing conditions, react with the newly deposited sulphur to form sulphur dioxide gas which readily leaves the reaction area along with the passing hydrocarbon vapor; with this series of operations repeating over and over. Thus, the oxygen will be added until the amount of sulphur removed from the hydrocarbon remains constant, regardless of the further addition of oxygen.

It has been found during the desulfurizing of a West Texas distillate containing 0.821 per cent sulfur that 1.25 cubic feet of oxygen per barrel (42 gallons) was sufiicient.

It is essential that the oxygen be added in the catalyst bed proper. It should not be premixed with the incoming oil vapor, since such premixing results in an excessive amount of hydrocarbon oxidation taking place, thereby damaging the product beyond repair for meeting standard specifications for such products.

Also, it has been found desirable to add the oxygen at several different points throughout the catalyst bed intermittently at the several diierent points and to alternate the points 'of entry by closing off some of the entry ports for a fixed time, say, for from 5 t0 7 minutes, and then re-establish the oxygen feed through the bed for a similar length of time. By following this procedure excessive over-heating at the points of entry of the oxygen is prevented, and the formation of coke, etc., is retarded.

It is not necessary that the incoming oxygen to the reactor be preheated, but, it is preferred that the temperature of the incoming oxygen be raised to that of the reaction chamber to eliminate the possibility of cooling the incoming oil vapor and, thus, prevent as far as possible the formation of tars which would be readily converted to coke which would soon plug the catalyst bed.

The oxidation of sulphur results in some discoloration of the resulting condensate which is undesirable in the trade. However, this is easily overcome by passing the vapors through an adsorbent clay such as is commonly used for the purpose of decolorizing petroleum products.

The pressure in the reaction chamber may vary from atmospheric to 250 lbs. gage. This may be determined by the requirement of the equipment in which the process is carried out.

As the result of the procedure, unsaturates such as olens present in the petroleum or formed during the distillation polymerize and condense in liquid form during the treatment of the vapors with the decolorizing clay. The polymers descend to the bottom of the decolorizing tower and are withdrawn, while the decolorized vapors escape to the condenser.

. Referring to the drawing, 5 indicates a suitable still in which the material to .be treated, i. e., crude petroleum or a distillate therefrom, is vaporized by the application of heat. The vapor is delivered through a pipe 6 to the bottom 0f a tower 1. Oxygen or a gas containing oxygen is introduced through pipes 8, 8a, 8b and 3C in the required proportions and mixed with the vapors of the petroleum hydrocarbon. The introduction of the oxygen or the oxygen-containing gas through the pipes 8, 8a, Ilb and 8c preferably is intermittent and in alternation so that excessive over-heating at the respective points of entry of the oxygen does not occur. The vapors pass upwardly through the tower 'I in intimate contact with the previously-described catalyst in the form of pellets or masses of suitable form, affording a large surface contact between the catalyst and the vapors and oxygen. The catalyst acts as an oxidizing catalyst, and, in the presence of oxygen, the sulphur compounds in the petroleum hydrocarbons are oxidized to sulphur dioxide.

'I'he vapors, including the sulphur dioxide, any excess of oxygen, and nitrogen, if it is mixed with the oxygen, escape through a pipe 9 to the bottom of a second column I0. 'I'he latter is filled with a decolorizing clay such as is commonly used for decolorizing petroleum products. The clay may be in the form of pellets or other masses arranged to permit the vapors to pass readily therethrough while the materials which color the product are separated. Among such materials are the unsaturates such as the olefins which may be present in the crude petroleum or may be formed during the operation. The unsaturates form polymers which are liquids and which descend through the column I0 and escape through a pipe II, collecting in a container I2.

The vapors from the column I0 are delivered through a pipe I3 to a condensing coil I4 disposed in a condenser I5 which may be cooled with water supplied through a pipe I6 and withdrawn through a pipe I'I. Water is ordinarily suilicient as a cooling agent, but if considerable amounts of nitrogen are present with the vapors, it may be necessary to cool at a lower temperature in which case cold brine or other suitable cooling means may be substituted for the cooling water. The condensate collects in a receptacle I8 and the sulphur dioxide and any remaining gases are vapors are withdrawn through a pipe I9.

Preferably the vapors introduced to the column 'I through the pipe 6 are heated to a temperature of between 750 and 850 F. If necessary, means may be employed to maintain the temperature of the vapors in the column 1, although normally that is not necessary. The temperature of the column I 0 may be that temperature to which the vapors normally drop in passing from the-fcolumn fl to fthe column m.. yUsuarllyjth'e temperature is 1intheoreiglfiborhood'Lofi60o The fconclensate received `in the :receptacle 118 iis a vwaterfwhite `condensate lfree cram r.coloring 'material and substantially free .from 'the :sulphur .I

compounds which-contaminate thepe'troleum,hy-- drocarbons which are ted `to `the system. 'The procedure .may :be employed zin :the treatment 'of crude ...petroleum `which nis vaponized `in `the :still 5, ytor -distillates irom @crude .petroleum rmay Qbe similarly treated.

Instead :of :initially ncharging 'the tower TI with the =catalyst 1 containing Icuprous sulphide, :it linitially 'may .be charged 'with la :similar @catalyst --exi cept that cupric :sulphide fis yused instead of cuprous sulphide, since, in .the .presence @of the gaseous voxygen the 'cupr'ic :sulphide will fbe iconventedgatfleastingpartto"ouprousrsulpliida'whioh thereafter will be effective do 'remove sulphur compounds from the hydrocarbon yapors.

The table set forth below shows the improved results vobtained by 'the `use fof "the lpres'ent method of desulphurizationcompared lto the present conventional procedure in E.the de'sulphurizaft-ion "of a West Texas pipe Yline crude :having :fa 32:5 A. P. I. gravity and a 1.60% total sulphur'content. g-In each instance :the catalytic ibed was maintained vat 350 FF., and lair was fa'dded fait -the rate -of 16.25 cu. att. per barrel 'of `corude.

The following tableshows the v"ortanes of the gasolines recovered by the I-a'bove two processes without the addition ofit'etraethylead, land'wlth 3 m1. of tetraethyl lead, respectively.

Produced by Present Procedure Produced by Conventional Procedure Various changes may be made in the form and arrangement of the apparatus and in the procedure as described without departing from the invention or sacrificing the advantages thereof.

This application is a continuation-in-part of my abandoned application Serial No. 63,408, filed December 3, 1948.

I claim:

1. The method of removing the major portion of all sulphur compounds contained in petroleum hydrocarbons which comprises oxidizing sulphur of the sulphur compounds to sulphur dioxide by passing the vapor of the hydrocarbon over an oxidation catalyst consisting essentially .fof Y a material containing cuprous sulphide in the presence of gaseous oxygen.

2. The method of claim 1 in which the oxygen is introduced directly into the catalyst mass.

3. The method of claim 2 in which the oxygen is introduced into the catalyst mass at av plurality of spaced points.

4. The method of claim 3 in which the oxygen is introduced intermittently and alternately at said spaced points.

V5. The .method ylof 'claim :l in 'which the wapors of the hydrocarbon fare ata temperature lbetween 55th-F. 1and1950 F. when ythey eare initially scontacte'd with the catalyst.

6. The method tof removing the major portion of all sulphur `compounds `contained petroleum hydrocarbons .which comprises oxidizing sulphur of @the sulphur compounds -to sulphur :dioxide 7by passing the vapor 'of the :hydrocarbon over yan oxidation catalyst consisting essentially -of a -material from the class consisting of cuprous sulphide, ia mixture of cuprous sulphide and 'an aluminum fsilicate, l'a mixture of cuprous sulphide :and 'alumina and `a `mixture 'of cuprous sulphide, .alumina and silica, `in the presence of foxygen, fand sepa-rating .the hydrocarbon in a liquid state from lthe sulphur `dioxide 'formed by 'the actionvof the catalyst.

il. The methodof fclam `6 in which the vapor'of lthe hydrocarbon is at a :temperature between 55.0 and-950 Ywhen litis initially contacted with the catalyst.

Y8. .The method of claim -6 lin `which the :vapor of the 1hydroc'arb'cul -iis at a temperature of be- V:tween 7501F. and 850F. when itis initially =con l tacte'd with the lcatalyst.

9. The method yof lremoving the Amajor portion of allisulphurlcompounds contained in petroleum hydrocarbons Which'comprise's oxidizing sulphur of the sulphur compounds :to sulphur dioxide by passing the vapor 'ofthe hydrocarbon-overnam oxidation catalyst consisting lessentially of a linaterial from the I'class vconsisting fof Icuprous sulphide, a 'mixture of ycuprous sulphide and an aluminum silicate, :a :mixture `of cuprous sulphide and ualumina and a mixture `of :cuprous sulphide, aluminarand silica, in the presenceofgaseousfoxygen, #removing color-forming fbodies :produced the vapor by fthe action of the catalyst, andseparating the hydrocarbon :in a liquid state from the :sulphur dioxide `formed .by :the action of the catalyst.

10. The method of removing the imajor :portion of all sulphur compounds contained in petroleum hydrocarbons which comprises oxidizing sulphur of the sulphur compounds to sulphur dioxide by passing the vapor of the hydrocarbon over an oxidation catalyst consisting essentially of a material from the class consisting of cuprous sulphide, a mixture of cuprous sulphide and an aluminum silicate, a mixture of cuprous sulphide and alumina and a mixture of cuprous sulphide, alumina and silica, in the presence of gaseous oxygen, removing color-forming bodies produced in the vapor by the action of the catalyst, separating in the liquid phase, the polymers formed as a result of the polymerization of the color-forming bodies, and condensing the remainder of the vapor to separate the hydrocarbon thereof in a liquid state from the sulphur dioxide formed by the action of the catalyst.

1l. The method of claim 1 in which the temperature of the oxygen added to the re-action zone is substantially that of the re-action zone.

12. The method of removing the major portion of all sulphur compounds contained in petroleum hydrocarbons which comprises oxidizing sulphur of the sulphur compounds to sulphur dioxide by passing the vapor of the hydrocarbon over an oxidation catalyst consisting essentially of a homogeneous mixture of cuprous sulphide and an aluminum silicate, in the presence of gaseous oxygen, and separating hydrocarbon in a liquid state from the sulphur dioxide formed by theaction of the catalyst.

13. The method of removing the major portion of all sulphur compounds contained in petroleum hydrocarbons which comprises oxidizing sulphur of the sulphur compounds to sulphur dioxide by passing the vapor of the hydrocarbon over an oxidation catalyst consisting essentially of a homogeneous mixture of cuprous sulphide and a silica-alumina material, in the presence of gaseous oxygen, and separating the hydrocarbon in a liquid state from the sulphur dioxide formed by the action of the catalyst.

14. The method of removing the major portion of all sulphur compounds contained in petroleum hydrocarbons which comprises oxidizing sulphur of the sulphur compounds to sulphur dioxide by passing the vapor of the hydrocarbon over an oxidation catalyst consisting essentially of a homogeneous mixture of cuprous sulphide and alumina, in the presence of gaseous oxygen, separating the hydrocarbon in a liquidstate from the sulphur dioxide formed by the action of the catalyst.

15. The method of removing the major portion of all sulphur compounds contained in petroleum hydrocarbons which comprises oxidizing sulphur of the sulphur compounds to sulphur dioxide by passing the vapor of the hydrocarbon over an oxidation catalyst consisting essentially of cuprous sulphide in the presence of gaseous oxygen, and separating the hydrocarbon in a liquid state from the sulphur dioxide formed by the action of the catalyst.

16. The method of removing the major portion of all sulphur compounds contained in petroleum hydrocarbons which comprises oxidizing sulphur of the sulphur compounds to sulphur dioxide by passing the vapor of the hydrocarbon at a temperature between '750 F. and 850 F. over an oxidation catalyst consisting essentially of cuprous sulphide in the presence of gaseous oxygen, and separating the hydrocarbon in a liquid state from the sulphur dioxide formed by the action of the catalyst.

17. The method of removing the major portion of all sulphur compounds contained in petroleum hydrocarbons which comprises oxidizing sulphur of the sulphur compounds to sulphur dioxide by passing the vapor of the hydrocarbon over an oxidation catalyst consisting essentially of cuprous sulphide in the presence of gaseous oxygen, removing color-forming bodies produced in the vapor by the action of the catalyst, and separating the hydrocarbon in a liquid state from the sulphur dioxide formed by the action of the catalyst.

18. The method of removing the major portion of all sulphur compounds contained in petroleum hydrocarbons which comprises oxidizing sulphur of the sulphur compounds to sulphur dioxide by passing the vapor of the hydrocarbon over an oxidation catalyst consisting essentially of cuprous sulphide in the presence of gaseous oxygen, removing color-forming bodies produced in the vapor by the action of the catalyst, separating in the liquid phase, the polymers formed as a result of the polymerization of the color-forming bodies, and condensing the remainder of the vapor to separate the hydrocarbon thereof in a liquid state from the sulphur dioxide formed by the action of the catalyst.

19. The method of claim 1 in which the catalyst is in the form of beads or pellets having a maxi-v mum length in any direction not substantially exceeding one-half inch.

` CHARLES O. HOOVER.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,840,158 Cross Jan. 5, 1932 2,042,053 Hoover s- May 26, 1936 2,228,041 Yabroft et al Jan. 7, 1941 FOREIGN PATENTS Number Country Date 588,765 Great Britain June 3, 1947 

1. THE METHOD OF REMOVING THE MAJOR PORTION OF ALL SULPHUR COMPOUNDS CONTAINED IN PETROLEUM HYDROCARBONS WHICH COMPRISES OXIDIZING SULPHUR OF THE SULPHUR COMPOUNDS TO SULPHUR DIOXIDE BY PASSING THE VAPOR OF THE HYDROCARBON OVER AN OXIDATION CATALYST CONSISTING ESSENTIALLY OF A MATERIAL CONTAINING CUPROUS SULPHIDE IN THE PRESENCE OF GASEOUS OXYGEN. 